In this Letter, we demonstrate
an efficient way to significantly increase the lossless bandwidth for such devices, by combining inverse design techniques [1]}, [2]}
with the semi-analytical approach to computing photonic band structures known as the guided mode expansion (GME) technique [3]}.
Starting with a state-of-the-art design from
He et al. [4]}, we show how to increase the bandwidth by more than 110\(\%\) , yielding
a significant operation bandwidth of 28.0 THz below the light line, with single mode operation that is compatible with telecom wavelengths. Moreover,
our methodology can be used to optimize many target figures of merit for PCS structures, in an intuitive and efficient way.
